Ready reckoner

Or: using multiples of 71 for fun and profit.

Why 71? Well, you know how a standard US 12-oz bottle is 355 mls, which is 5×71, whereas an imperial pint is 568 mls or 8×71? Well, you do now. And you know how 14 71s is 994, meaning that an imperial pint is near as dammit 8/14s or 4/7s of a litre? Well, thank me later.

You can probably see where I’m going with this.

Third

Half

330 ml

12 oz US

2/3 pint

500 ml

Pint

Third

=

2/3

4/7

8/15

1/2

8/21

1/3

Half

3/2

=

6/7

4/5

3/4

4/7

1/2

330 ml

7/4

7/6

=

14/15

7/8

2/3

7/12

12 oz US

15/8

5/4

15/14

=

15/16

5/7

5/8

2/3 pint

2/1

4/3

8/7

16/15

=

16/21

2/3

500 ml

21/8

4/7

3/2

7/5

21/16

=

7/8

Pint

3/1

2/1

12/7

8/5

3/2

8/7

=

To use, pick one row – or column – and memorise it; you can derive all the rest from it. Either that or print it out.

(As for why you’d want to use it, haven’t you ever wondered how to compare a pint at 6%, a 500 ml bottle at 6.8% and a US 12 oz-er at 9.6%? Now you know: they’re all exactly as strong as each other.)

UPDATE Removed the ‘US Pint’ entries and added ‘2/3’, that being a measure people reading this are actually likely to see.

One Comment

Reminds me of how I hated maths at school. Fucked if I understand how to use it. Well I sort of do as I have an O Level Arithmetic from 1972, but I’ll have to cut out, keep and use a calculator. Clever though.